In the field of electronic keyboard musical instruments and the like keyboard musical instruments, there have been known such keyboard assemblies as have a plurality of playing keys which are formed of a resin material and are swingably supported at their rear ends by a keyboard frame, as shown, for example, in unexamined Japanese patent publication No. 2001-215968. In such a keyboard assembly, each of a plurality of playing keys has a key body to be depressed by a player and an elastically deformable thickness-reduced member integrally extending vertically downward from the rear end of each key body, and the plurality of thickness-reduced members (for the plurality of key bodies each) are integrally connected to a common connecting member to horizontally align the key bodies in the direction of juxtaposition to constitute a multikey unit. The keyboard frame, on the other hand, has a vertical rear wall member to which is fixed the common connecting member of the multikey unit. Such a configuration is advantageous in minimizing the total depth of the keyboard assembly.
In such a conventional keyboard assembly, however, as the rear top wall member and the vertical rear wall member are formed perpendicular to each other, the configuration is disadvantageous in assembling the multikey unit to the keyboard frame, as the lower edge of the common connecting member of the multikey unit may bump against and be caught on the rear top wall member when the multikey unit is being mounted on the keyboard frame. Particularly in the case of a keyboard assembly which has swing mechanisms (e.g. swing weights) to simulate the key touch feeling of an acoustic piano, each of the key bodies is provided with an actuating member to actuate the associated swing mechanism, and accordingly the actuating members have to be engaged with the swing mechanisms in the course of mounting the multikey unit onto the keyboard frame. Such a procedure is likely to cause the lower edge of the common connecting member to bump against and be caught on the rear end of the rear top wall member. And further, the conventional keyboard assembly does not have a particular structure for accurately positioning the common connecting member during the assemblage of the multikey unit and the keyboard frame.